Project Summary: Advancing the work from my current post doctoral position is the more immediate goal described in this application as two specific aims. Relative to the first aim, different closely related viruses have adapted to bind the same host protein in a variety of ways, suggesting a convergent evolution that offers an advantage to the virus. The viral adaptation to bind this protein also alters pathogenicity. Using a structural approach to map the area of interaction on the surface of the virus may provide insights into the pathogenic consequences of receptor usage, and complement the existing mutational studies. The second aim is directed at understanding the asymmetric use of a host protein by a parvovirus. The binding of only one soluble receptor molecule in vitro was unexpected and exciting. Possibly, binding receptor instigates a conformational change to the virus and formation of an asymmetric feature critical to continue infection, perhaps leading to the uncoating of the genome. Alternatively, the small icosahedral virus may not be as perfectly symmetrical as structural studies have previously suggested. Averaging techniques used widely in structural determinations may have ultimately hidden from view the presence of functional asymmetric features in this virus and other viral systems. The aim is to investigate both possibilities. The study of viral assembly in my doctoral work, led to a post doc where I have learned both cryoEM reconstruction techniques and X-ray crystallography. The projects outlined in this application will use both techniques and provide the opportunity to delve deeper into the program suites for reconstruction, past knowledge of theory and merely how to use particular programs. To be truly creative in problem solving requires a comprehensive computational understanding of the specific algorithms and routines in order to tailor a reconstruction process to the data at hand and achieve the highest quality results. This transition period will allow me to proceed toward the ultimate goal of continuing independent research in viral structure in an academic setting, making worthy contributions to the field, and providing the opportunity to pass on the skills and the enthusiasm for science that have been instilled in me. Relevance: Picornaviruses cause severe myocarditis, aseptic meningitis and are implicated in diabetes. This study will investigate the contribution of receptor binding to pathogenicity. Receptor usage in parvoviruses may lead to functionally necessary deviations from exact icosahedral symmetry. A better understanding of this phenomenon may provide an exact target for antivirals and have broader application in other systems. Furthermore, study of canine parvovirus in particular may lead to clarification of species jumping.